A combined preparation apparatus and method for methylhydrazine

Abstract

This invention belongs to the field of methylhydrazine preparation technology, and particularly relates to a combined methylhydrazine preparation apparatus and method. The combined methylhydrazine preparation apparatus includes an evaporator crystallizer, a forced circulation evaporator, a distillation column, a crystallization circulation pump, a thickener, a falling film evaporator, a thermosiphon reboiler, a falling film circulation pump, a forced circulation pump, a bottom pump, and a horizontal centrifuge. The methylhydrazine feedstock enters the evaporator crystallizer, where the material is circulated by the forced circulation pump. Forced circulation evaporators are installed at the inlet and outlet of the forced circulation pump to heat the material. The top steam of the distillation column is used as the heat source. The evaporated gas in the evaporator crystallizer enters the distillation column under pressure. Salts in the feed are enriched and crystallized out, then transported by the crystallization circulation pump to the thickener for temporary storage. This replaces the original process of steam + vacuum pump + multi-effect evaporation crystallization, employing distillation + MVR evaporation crystallization, reducing process costs, improving process efficiency, and increasing market product profits.

Description

Technical Field

[0001] This invention belongs to the field of methylhydrazine preparation technology, specifically a methylhydrazine combined preparation apparatus and preparation method. Background Technology

[0002] Methylhydrazine solution is a chemical substance. In the preparation process, methylhydrazine raw material needs to be fed into an evaporator crystallizer to form evaporation crystals. After evaporation crystallization, methylhydrazine solution will be formed in a distillation column. The distillation column is equipped with a heat source, which is a necessary condition for the formation of methylhydrazine solution.

[0003] However, the above-mentioned technologies often have the following drawbacks: the current methylhydrazine solution consumes a lot of raw materials during the entire preparation process, requires a large amount of heat source to generate steam, and is accompanied by a large amount of circulating water consumption, resulting in high cost, outdated technology, and low market product profits for methylhydrazine. Therefore, this utility model provides a methylhydrazine co-preparation device and preparation method. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A methylhydrazine co-preparation apparatus according to this invention includes an evaporator crystallizer, a forced circulation evaporator, a distillation column, a crystallization circulation pump, a thickener, a falling film evaporator, a thermosiphon reboiler, a falling film circulation pump, a forced circulation pump, a bottom pump, and a horizontal centrifuge; characterized in that: the evaporator crystallizer is connected to the forced circulation pump via a pipeline; the inlet and outlet of the forced circulation pump are respectively equipped with forced circulation evaporators; the evaporator crystallizer is located inside the distillation column; the evaporator crystallizer is connected to the crystallization circulation pump via a pipeline; the crystallization circulation pump is connected to the thickener via a pipeline; the falling film evaporator, the thermosiphon reboiler, and the falling film circulation pump are located at the bottom of the distillation column; the outlet of the bottom pump is connected to a discharge pipe; the methylhydrazine feedstock enters the evaporator crystallizer; the material inside the evaporator crystallizer is propelled by the forced circulation pump to establish circulation, and the material is then circulated within the forced circulation pump. Forced circulation evaporators are installed at both the pump inlet and outlet to heat the material, using the top steam of the distillation column as the heat source. The evaporated gas in the evaporator crystallizer enters the distillation column under pressure. After salts are enriched in the feed, they crystallize and precipitate, and are transported to the thickener for temporary storage by the crystallization circulation pump. Then, they enter the horizontal centrifuge for solid-liquid separation. The solid salts are discharged, and the liquid mother liquor is temporarily stored in the mother liquor tank and pressurized by the mother liquor pump before returning to the evaporator crystallizer. The evaporated crystallized gas phase enters the distillation column. At this time, the falling film circulation pump provides power for the material circulation. The falling film evaporator is the main heat source, using the pressurized top steam of the column as the heat source, and the thermosiphon reboiler is the auxiliary heat source, using external make-up steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as the product by the bottom pump and then discharged from the discharge pipe. This replaces the original process of using steam + vacuum pump + multi-effect evaporation crystallization. The process adopts distillation + MVR evaporation crystallization, which reduces process costs, improves process efficiency, and increases market product profits.

[0006] Preferably, the distillation column is equipped with a demister, a steam compressor, a reflux tank, and a condenser at the top. The reflux tank is connected to a reflux pump via a pipeline. The steam at the top of the column enters the steam compressor through the demister, is pressurized, and then sent to the shell side of the falling film evaporator. It exchanges heat with the circulating material in the tube side, condenses, and enters the reflux tank. After being pressurized by the reflux pump, part of it is refluxed and part is collected as wastewater. The liquid generated by the steam compressor enters the liquid collection tank and is then sent to the reflux tank by the liquid collection pump. This process uses the steam compressor as a heat source, reduces steam consumption and circulating water consumption, and refluxes part of the liquid formed by the steam, thereby reducing the cost in the process of producing methylhydrazine solution.

[0007] Preferably, an electrical guide rail is fixedly connected to the surface of the distillation column near the bottom. A guide block is slidably connected to the inner wall of the electrical guide rail. A magnetic block is provided on the top surface of the guide block. A cleaning block made of magnetic material is attached to the inner wall of the distillation column, and the cleaning block and the magnetic block are magnetically attracted. Since a methylhydrazine aqueous solution will be concentrated at the bottom of the distillation column, some solution will adhere to the inner wall of the bottom of the distillation column, causing the bottom pump to be unable to completely collect the methylhydrazine aqueous solution. At this time, the above mechanism can be used to activate the electrical guide rail to drive the guide block to slide during the solution collection process. The magnetic block will move with the guide block, thereby driving the cleaning block, which is magnetically attracted to the magnetic block, to move inside the distillation column. The cleaning block can then scrape off the solution adhering to the inner wall of the distillation column and enter the bottom of the distillation column, where it will be collected by the bottom pump, thereby improving the solution collection efficiency.

[0008] Preferably, the magnetic block is slidably connected to the top surface of the slider, a driving block is fixedly connected to the top surface of the magnetic block, one side of the driving block is inclined, a set of round rods for pushing the driving block is fixedly connected to the outer wall of the distillation column, a hollow connecting ring is fixedly connected to the inner wall of the distillation column, the bottom surface of the connecting ring has an annular groove communicating with its interior, a connecting rod passing through the groove is fixedly connected to the top surface of the cleaning block, a connecting plate is fixedly connected to the top of the connecting rod, and the side wall of the connecting plate fits against the inner wall of the connecting ring; when the guide block slides, the round rod (with a gap between the round rod and the magnetic block) pushes the inclined surface of the driving block, at which time the magnetic block slides upward under the drive of the driving block, and then the round rod completely passes through... After the drive block is activated, the magnetic block moves downwards. During this process, the magnetic block drives the cleaning block to move up and down, causing the cleaning block to shake. At this time, the solution accumulated on the side wall of the cleaning block (the side wall scrapes the solution on the inner wall of the distillation column, leaving a lot of solution on the side wall) and its own residual solution can be shaken off. Since the cleaning block is magnetically attached to the magnetic block in the distillation column, the cleaning block will be unstable when rotating in the distillation column, especially when shaking. After the cleaning block moves downwards, the connecting plate will contact the bottom surface of the inner wall of the connecting ring. Then, when the cleaning block rotates, the slide rod will be guided by the slide groove, thereby limiting the cleaning block to the inner wall of the distillation column and improving the stability of the cleaning block in the distillation column.

[0009] Preferably, a U-shaped collecting block is fixedly connected to the surface of the cleaning block. The collecting block is close to the inner wall of the distillation column on both sides, and one of the sides has a liquid outlet. The position of the liquid outlet is aligned with the middle part of the discharge pipe. The top surface of the collecting block is open, and the collecting block is made of elastic material. After the liquid at the bottom of the distillation column is discharged, there will still be residual liquid on the collecting block flowing to the bottom of the distillation column. The residual liquid is very small, and at this time, this liquid will not reach the liquid level to be pumped away by the bottom pump. The above mechanism can collect the liquid flowing on the cleaning block with the help of the collecting block. When it is necessary to discharge the liquid in the collecting block, simply move the cleaning block to the discharge pipe. At this time, the two side walls of the collecting block will extend into the discharge pipe due to elasticity, so that the liquid outlet extends into the discharge pipe. At this time, the liquid in the collecting block can flow directly from the liquid outlet into the discharge pipe and be discharged, thereby further improving the liquid discharge effect.

[0010] Preferably, a sponge block is fixedly connected to the open end of the collection block. During the movement of the cleaning block, it shakes, causing the liquid accumulated inside to easily spill out. Since the bottom of the distillation column is equipped with a falling film evaporator, a thermosiphon reboiler, and a falling film circulation pump, the spilled liquid is difficult to clean when it falls onto these devices. The sponge block seals the opening of the collection block, allowing the liquid sliding off the cleaning block to permeate through the sponge block and enter the collection block. When the cleaning block shakes, the sponge block blocks the liquid inside, improving the liquid collection effect.

[0011] Preferably, a magnetic plate is fixedly connected inside the discharge pipe, and a pressure plate that attracts the magnetic plate is fixedly connected to the side of the collection block away from the inner wall of the distillation column. The pressure plate is made of magnetic material. When the collection block moves to the discharge pipe, the magnetic plate will magnetically attract the pressure plate. At this time, the pressure plate will squeeze the collection block, thereby squeezing the sponge block. The liquid absorbed by the sponge block can then flow into the collection block and then be discharged from the discharge pipe. Through the above mechanism, the sponge block is squeezed, thereby allowing the liquid absorbed by the sponge block to be discharged.

[0012] Preferably, guide blocks are fixedly connected to both sides of the inner wall of the collecting block. The top surface of the guide block is inclined, and the guide block is uniformly provided with round holes that communicate with the inside of the collecting block. When the sponge block is squeezed, the liquid will spread from the periphery of the sponge block. At this time, the liquid that spreads to the top of the sponge block will flow onto the guide block and then flow into the collecting block from the round holes.

[0013] Preferably, a hollow elastic block is fixedly connected inside the sponge block, and an air vent is provided on the bottom surface of the elastic block. When the sponge block is squeezed, the elastic block is also squeezed. At this time, air will be blown out through the air vent, thereby blowing away the liquid accumulated at the bottom of the sponge block, improving the effect of liquid discharge when the sponge block is squeezed. At the same time, the gas can also be blown into the collection block, which will agitate the liquid inside the collection block, allowing the liquid to be discharged from the liquid outlet better.

[0014] This invention also provides a method for the combined preparation of methylhydrazine, using the aforementioned apparatus for the combined preparation of methylhydrazine. The method includes the following steps:

[0015] S1: Methylhydrazine feedstock is transported to the evaporator crystallizer via pipeline. The material in the crystallizer is circulated by a forced circulation pump. Forced circulation evaporators are set at the inlet and outlet of the forced circulation pump to heat the material, using the top steam of the distillation column as the heat source.

[0016] S2: The evaporated gas in the evaporator crystallizer enters the distillation column under its own pressure. After the salts in the feed are enriched, they crystallize and precipitate. The crystallization circulation pump transports the precipitator to the thickener for temporary storage. The precipitator then enters the horizontal centrifuge for solid-liquid separation. The solid salts are discharged, and the liquid mother liquor is temporarily stored in the mother liquor tank and pressurized by the mother liquor pump before returning to the evaporator crystallizer.

[0017] S3: The vapor phase of the evaporated crystals enters the distillation column. At this time, the falling film circulation pump provides power for the material circulation. The falling film evaporator is the main heat source, using pressurized top steam as the heat source. The thermosiphon reboiler is the auxiliary heat source, using external steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as a product by the bottom pump and then discharged from the discharge pipe, completing the co-preparation of p-methylhydrazine.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. Methylhydrazine feedstock enters the evaporator crystallizer. The material inside the evaporator crystallizer is circulated by a forced circulation pump. Forced circulation evaporators are installed at both the inlet and outlet of the forced circulation pump to heat the material, using the top steam of the distillation column as the heat source. The evaporated gas in the evaporator crystallizer enters the distillation column under pressure. Salts in the feed are enriched and crystallized out, then transported by a crystallization circulation pump to a thickener for temporary storage. From there, a horizontal centrifuge performs solid-liquid separation. Solid salts are discharged, and the liquid mother liquor is temporarily stored in a mother liquor tank and pressurized by a mother liquor pump before returning to the evaporator crystallizer. The evaporated crystallized gas phase enters the distillation column. At this point, a falling film circulation pump provides power for the material circulation. The falling film evaporator is the primary heat source, using pressurized top steam as the heat source, while the thermosiphon reboiler provides auxiliary heat, using external makeup steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as the product by a bottom pump and then discharged through a discharge pipe. This replaces the original process of using steam + vacuum pump + multi-effect evaporation crystallization, adopting distillation + MVR evaporation crystallization, reducing process costs, improving process efficiency, and increasing market product profits.

[0020] 2. The steam at the top of the tower enters the steam compressor through the demister. After being pressurized, it is sent to the shell side of the falling film evaporator, where it exchanges heat with the circulating material in the tube side and condenses into the reflux tank. After being pressurized by the reflux pump, part of it is refluxed and part is collected as wastewater. The liquid generated by the steam compressor enters the liquid collection tank and is sent to the reflux tank by the liquid collection pump. This process uses the steam compressor as a heat source, reducing steam consumption and circulating water consumption. The reflux of part of the liquid formed by the steam reduces the cost in the process of producing methylhydrazine solution. Attached Figure Description

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Figure 1 This is a diagram showing the device layout in this invention;

[0023] Figure 2 This is a perspective view of the distillation column in this invention;

[0024] Figure 3 This is a schematic diagram of the internal structure of the distillation column in this invention;

[0025] Figure 4 yes Figure 2 Enlarged view of point A;

[0026] Figure 5 This is a schematic diagram of the connecting ring structure in this invention;

[0027] Figure 6 yes Figure 5 Enlarged view of point B;

[0028] Figure 7 This is a schematic diagram of the structure of the collecting block in this invention;

[0029] Figure 8 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0030] Figure 9 This is a flowchart of the method in this invention.

[0031] In the diagram: 1. Distillation column; 2. Forced circulation pump; 3. Crystallization circulation pump; 4. Reflux pump; 5. Falling film circulation pump; 6. Bottom pump; 7. Forced circulation evaporator; 8. Falling film evaporator; 9. Thermosiphon reboiler; 10. Condenser; 11. Evaporation crystallizer; 12. Thickener; 13. Defoamer; 14. Reflux tank; 15. Steam compressor; 16. Discharge pipe; 17. Connecting ring; 18. Slide rail; 19. Connecting rod; 20. Connecting plate; 21. Cleaning block; 22. Electrical guide rail; 23. Guide block; 24. Magnetic block; 25. Round rod; 26. Drive block; 27. Collection block; 28. Liquid outlet; 29. ​​Sponge block; 30. Pressure plate; 31. Guide block; 32. Round hole; 33. Magnetic plate; 34. Elastic block; 35. Gas outlet; 36. Horizontal centrifuge. Detailed Implementation

[0032] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0033] Example 1: As Figures 1 to 7 As shown in the embodiment of the present invention, a methylhydrazine co-preparation apparatus includes an evaporator crystallizer 11, a forced circulation evaporator 7, a distillation column 1, a crystallization circulation pump 3, a thickener 12, a falling film evaporator 8, a thermosiphon reboiler 9, a falling film circulation pump 5, a forced circulation pump 2, a bottom pump 6, and a horizontal centrifuge 36; characterized in that: the evaporator crystallizer 11 is connected to the forced circulation pump 2 via a pipeline; the inlet and outlet of the forced circulation pump 2 are respectively provided with the forced circulation evaporator 7; the evaporator crystallizer 11 is disposed inside the distillation column 1; the evaporator crystallizer 11 is connected to the crystallization circulation pump 3 via a pipeline; the crystallization circulation pump 3 is connected to the thickener 12 via a pipeline; the falling film evaporator 8, the thermosiphon reboiler 9, and the falling film circulation pump 5 are disposed at the bottom of the distillation column 1; and the outlet of the bottom pump 6 is connected to a discharge pipe 16;

[0034] Methylhydrazine feedstock enters evaporator crystallizer 11. The material inside evaporator crystallizer 11 is circulated by forced circulation pump 2. Forced circulation evaporators 7 are installed at the inlet and outlet of forced circulation pump 2 to heat the material, using the top steam of distillation column 1 as a heat source. The evaporated gas in evaporator crystallizer 11 enters distillation column 1 under pressure. After salts are enriched in the feed, they crystallize and precipitate, and are transported to thickener 12 for temporary storage by crystallization circulation pump 3. The solids are then separated by horizontal centrifuge 36. Solid salts are discharged, and the liquid mother liquor is temporarily stored in mother liquor tank and pressurized by mother liquor pump. The vapor phase returns to the evaporator crystallizer 11 and enters the distillation column 1. At this time, the falling film circulation pump 5 provides power for the material circulation. The falling film evaporator 8 is the main heat source, using pressurized top steam as the heat source. The thermosiphon reboiler 9 is the auxiliary heat source, using external make-up steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as a product by the bottom pump 6 and then discharged from the discharge pipe 16. This replaces the original process of using steam + vacuum pump + multi-effect evaporation crystallization. The process adopts distillation + MVR evaporation crystallization, which reduces process costs, improves process efficiency, and increases market product profits.

[0035] The distillation column 1 is equipped with a demister 13, a steam compressor 15, a reflux tank 14, and a condenser 10 at its top. The reflux tank 14 is connected to a reflux pump 4 via a pipeline. The steam at the top of the column enters the steam compressor 15 through the demister 13, is pressurized, and then sent to the shell side of the falling film evaporator 8. It exchanges heat with the circulating material in the tube side and condenses into the reflux tank 14. After being pressurized by the reflux pump 4, part of it is refluxed and part is collected as wastewater. The liquid generated by the steam compressor 15 enters the liquid collection tank and is then sent to the reflux tank 14 by the liquid collection pump. This process uses the steam compressor 15 as a heat source, reduces steam consumption and circulating water consumption, and refluxes part of the liquid formed by the steam, thereby reducing the cost in the process of producing methylhydrazine solution.

[0036] An electric rail 22 is fixedly connected to the surface of the distillation column 1 near the bottom. A guide block 23 is slidably connected to the inner wall of the electric rail 22. A magnetic block 24 is provided on the top surface of the guide block 23. A cleaning block 21 made of magnetic material is attached to the inner wall of the distillation column 1. The cleaning block 21 and the magnetic block 24 are magnetically attracted.

[0037] Because a concentrated aqueous solution of methylhydrazine forms at the bottom of distillation column 1, some solution adheres to the inner wall of the bottom of distillation column 1, preventing the bottom pump 6 from completely extracting the aqueous solution. At this point, the aforementioned mechanism can activate the electric guide rail 22 to slide the guide block 23 during solution extraction. The magnetic block 24 moves along with the guide block 23, thereby moving the cleaning block 21, which is magnetically attracted to the magnetic block 24, within distillation column 1. The cleaning block 21 then scrapes off the solution adhering to the inner wall of distillation column 1, allowing it to reach the very bottom of distillation column 1 and be extracted by the bottom pump 6, thus improving the solution extraction efficiency.

[0038] The magnetic block 24 is slidably connected to the top surface of the slider. A driving block 26 is fixedly connected to the top surface of the magnetic block 24. One side of the driving block 26 is inclined. A set of round rods 25 that push the driving block 26 are fixedly connected to the outer wall of the distillation column 1. A hollow connecting ring 17 is fixedly connected to the inner wall of the distillation column 1. An annular groove 18 communicating with the inside of the connecting ring 17 is opened on the bottom surface of the connecting ring 17. A connecting rod 19 passing through the groove 18 is fixedly connected to the top surface of the cleaning block 21. A connecting plate 20 is fixedly connected to the top end of the connecting rod 19. The side wall of the connecting plate 20 is in contact with the inner wall of the connecting ring 17.

[0039] As the guide block 23 slides, the round rod 25 (with a gap between the round rod 25 and the magnetic block 24) pushes the inclined surface of the drive block 26. At this time, the magnetic block 24 slides upward under the drive block 26. Then, after the round rod 25 has completely passed the drive block 26, the magnetic block 24 moves downward. During this process, the magnetic block 24 drives the cleaning block 21 to move up and down, causing the cleaning block 21 to shake. At this time, the solution accumulated on the side wall of the cleaning block 21 (the side wall will scrape the solution on the inner wall of the distillation column 1, leaving a large amount of solution on the side wall) is removed. The residual solution can be shaken off. Since the cleaning block 21 is magnetically attached to the magnetic block 24 inside the distillation column 1, the cleaning block 21 will be unstable when it rotates inside the distillation column 1, especially when it is shaken. At this time, after the cleaning block 21 moves downward, the connecting plate 20 will contact the bottom surface of the inner wall of the connecting ring 17. Then, when the cleaning block 21 rotates, the slide bar will be guided by the slide groove 18, thereby limiting the cleaning block 21 to the inner wall of the distillation column 1 and improving the stability of the cleaning block 21 inside the distillation column 1.

[0040] The surface of the cleaning block 21 is fixedly connected with a "U"-shaped collection block 27. The collection block 27 is close to the inner wall of the distillation column 1 on both sides, and one of the sides is provided with a liquid outlet hole 28. The position of the liquid outlet hole 28 is aligned with the middle part of the discharge pipe 16. The top surface of the collection block 27 is open, and the collection block 27 is made of elastic material.

[0041] After the liquid at the bottom of the distillation column 1 is discharged, there will still be residual liquid flowing to the bottom of the distillation column 1 on the collection block 27. The residual liquid is very small, and at this time, the liquid will not reach the liquid level that is pumped away by the bottom pump 6. The above mechanism can collect the liquid flowing on the cleaning block 21 with the help of the collection block 27. When it is necessary to discharge the liquid in the collection block 27, simply move the cleaning block 21 to the discharge pipe 16. At this time, the two side walls of the collection block 27 will extend into the discharge pipe 16 due to elasticity, so that the liquid outlet 28 extends into the discharge pipe 16. At this time, the liquid in the collection block 27 can flow directly from the liquid outlet 28 into the discharge pipe 16 for discharge, thereby further improving the liquid discharge effect.

[0042] A sponge block 29 is fixedly connected to the open end of the collection block 27. When the cleaning block 21 moves, it will shake, and the liquid accumulated in the cleaning block 21 will easily be shaken off and scattered everywhere. Since the bottom of the distillation column 1 is equipped with a falling film evaporator 8, a thermosiphon reboiler 9, and a falling film circulation pump 5, the shaken liquid will be difficult to clean when it falls on these devices. At this time, by setting the sponge block 29, the opening of the collection block 27 can be sealed. The liquid that slides off the cleaning block 21 will permeate the sponge block 29 and enter the collection block 27. When the cleaning block 21 shakes, the sponge block 29 will block the liquid inside, improving the liquid collection effect.

[0043] A magnetic plate 33 is fixedly connected inside the discharge pipe 16. A pressure plate 30, which is attracted to the magnetic plate 33, is fixedly connected to the side of the collection block 27 away from the inner wall of the distillation column 1. The pressure plate 30 is made of magnetic material. When the collection block 27 moves to the discharge pipe 16, the magnetic plate 33 will be magnetically attracted to the pressure plate 30. At this time, the pressure plate 30 will squeeze the collection block 27, thereby squeezing the sponge block 29. The liquid absorbed by the sponge block 29 can flow into the collection block 27 and then be discharged from the discharge pipe 16. The above mechanism achieves the squeezing effect on the sponge block 29, so that the liquid absorbed by the sponge block 29 can be discharged.

[0044] Guide blocks 31 are fixedly connected to both sides of the inner wall of the collection block 27. The top surface of the guide block 31 is inclined, and the guide block 31 is evenly provided with round holes 32 that communicate with the inside of the collection block 27. When the sponge block 29 is squeezed, the liquid will spread from the periphery of the sponge block 29. At this time, the liquid that spreads to the top of the sponge block 29 will flow onto the guide block 31 and then flow into the collection block 27 through the round holes 32.

[0045] Example 2: Figure 8As shown in the comparative embodiment one, another embodiment of the present invention is as follows: a hollow elastic block 34 is fixedly connected inside the sponge block 29, and an air outlet 35 is provided on the bottom surface of the elastic block 34; when the sponge block 29 is squeezed, the elastic block 34 is also squeezed, and at this time the air outlet 35 will blow air, thereby blowing away the liquid accumulated on the bottom of the sponge block 29, improving the effect of liquid discharge when the sponge block 29 is squeezed. At the same time, the gas can also be blown into the collection block 27, at which time the gas will blow the liquid in the collection block 27, allowing the liquid to be discharged better from the liquid outlet 28.

[0046] like Figure 9 As shown, the present invention also provides a method for the combined preparation of methylhydrazine, which uses the above-mentioned apparatus for the combined preparation of methylhydrazine and includes the following steps:

[0047] S1: Methylhydrazine raw material is transported to the evaporator crystallizer 11 through a pipeline. The material in the crystallizer is circulated by the forced circulation pump 2. Forced circulation evaporators 7 are set at the inlet and outlet of the forced circulation pump 2 to heat the material, using the top steam of the distillation column 1 as the heat source.

[0048] S2: The evaporated gas in the evaporator crystallizer 11 enters the distillation column 1 by self-pressure. After the salts in the feed are enriched, they crystallize and precipitate. The crystallization circulation pump 3 transports the precipitator to the thickener 12 for temporary storage. The solids are then separated by the horizontal centrifuge 36. The solid salts are discharged, and the liquid mother liquor is temporarily stored in the mother liquor tank and pressurized by the mother liquor pump before returning to the evaporator crystallizer 11.

[0049] S3: The vapor phase of the evaporated crystals enters the distillation column 1. At this time, the falling film circulation pump 5 provides power for the material circulation. The falling film evaporator 8 is the main heat source, using the pressurized top steam as the heat source. The thermosiphon reboiler 9 is the auxiliary heat source, using the external make-up steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as a product by the bottom pump 6 and then discharged from the discharge pipe 16, completing the joint preparation of p-methylhydrazine.

[0050] Working Principle: Methylhydrazine feedstock enters the evaporator crystallizer 11. The material inside the evaporator crystallizer 11 is circulated by the forced circulation pump 2. Forced circulation evaporators 7 are installed at the inlet and outlet of the forced circulation pump 2 to heat the material. The steam from the top of the distillation column 1 is used as the heat source. The evaporated gas in the evaporator crystallizer 11 enters the distillation column 1 under pressure. Salts in the feed are enriched and crystallized out, then transported by the crystallization circulation pump 3 to the thickener 12 for temporary storage. The solid-liquid phase is then separated by the horizontal centrifuge 36. The solid salts are discharged, and the liquid mother liquor is temporarily stored in the mother liquor tank and pressurized by the mother liquor pump before returning to the evaporator crystallizer 11. The evaporated crystallized gas phase enters the distillation column 1. At this time, the falling film circulation pump 5 provides power for the material circulation. The falling film evaporator 8 is the main heat source, using pressurized top steam as the heat source, and the thermosiphon reboiler 9 is the auxiliary heat source, using external make-up steam. The heat source, the concentrated methylhydrazine aqueous solution at the bottom of the tower is collected as a product by the bottom pump 6 and then discharged from the discharge pipe 16, replacing the original process of using steam + vacuum pump + multi-effect evaporation crystallization. The process adopts distillation + MVR evaporation crystallization, which reduces process costs, improves the process, and increases market product profits. The steam at the top of the tower enters the steam compressor 15 through the demister tank 13. After being pressurized, it is sent to the shell side of the falling film evaporator 8, where it exchanges heat with the circulating material in the tube side and condenses into the reflux tank 14. After being pressurized by the reflux pump 4, part of it is refluxed and part is collected as wastewater. The liquid generated by the steam compressor 15 enters the liquid collection tank and is sent to the reflux tank 14 by the liquid collection pump. This process uses the steam compressor 15 as a heat source, reduces steam consumption and circulating water consumption, and refluxes part of the liquid formed by the steam, which reduces the cost in the process of producing methylhydrazine solution.

[0051] Because a concentrated aqueous solution of methylhydrazine forms at the bottom of distillation column 1, some solution adheres to the inner wall of the bottom of column 1, preventing the bottom pump 6 from completely collecting the aqueous solution. The aforementioned mechanism allows for solution collection by activating the electric guide rail 22 to slide the guide block 23. The magnetic block 24 moves along with the guide block 23, thus moving the cleaning block 21, which is magnetically attracted to the magnetic block 24, within the distillation column 1. The cleaning block 21 scrapes away the solution adhering to the inner wall of the distillation column 1, allowing the solution to reach the bottom of the column and be collected by the bottom pump 6, thereby improving the solution collection efficiency. As the guide block 23 slides, the round rod 25 (with a gap between the round rod 25 and the magnetic block 24) pushes the inclined surface of the drive block 26, causing the magnetic block 24 to slide upwards under the drive block 26. After the round rod 25 has completely passed the drive block 26, the magnetic block 24 will move downward. During this process, the magnetic block 24 will drive the cleaning block 21 to move up and down, thereby causing the cleaning block 21 to shake. At this time, the solution accumulated on the side wall of the cleaning block 21 (the side wall will scrape the solution on the inner wall of the distillation column 1, and at this time, a lot of solution will remain on the side wall) and its own residual solution can be shaken off. Since the cleaning block 21 is magnetically attached to the magnetic block 24 in the distillation column 1, the cleaning block 21 will be unstable when rotating in the distillation column 1, especially when shaking, the stability will be worse. At this time, after the cleaning block 21 moves downward, the connecting plate 20 will contact the bottom surface of the inner wall of the connecting ring 17. Then, when the cleaning block 21 rotates, the slide rod will be guided by the slide groove 18, thereby limiting the cleaning block 21 to the inner wall of the distillation column 1, improving the stability of the cleaning block 21 in the distillation column 1.

[0052] The liquid flowing on the cleaning block 21 is collected using the collecting block 27. When the liquid in the collecting block 27 needs to be discharged, simply move the cleaning block 21 to the discharge pipe 16. At this time, the two side walls of the collecting block 27 will extend into the discharge pipe 16 due to elasticity, thereby extending the liquid outlet 28 into the discharge pipe 16. The liquid in the collecting block 27 can then flow directly from the liquid outlet 28 into the discharge pipe 16 for discharge, thus further improving the liquid discharge effect. During the movement of the cleaning block 21, it will shake, and the liquid accumulated in the cleaning block 21 will easily be shaken off and scattered everywhere. Since the bottom of the distillation column 1 is equipped with a falling film evaporator 8, a thermosiphon reboiler 9, and a falling film circulation pump 5, the shaken liquid will be difficult to clean when it falls on these devices. At this time, by setting up the sponge block 29, the liquid can be cleaned up at the opening of the collecting block 27. When the cleaning block 21 is sealed, the liquid that slides off the cleaning block 21 will permeate the sponge block 29 and enter the collecting block 27. When the cleaning block 21 is shaken, the sponge block 29 will block the liquid inside, improving the liquid collection effect. When the collecting block 27 moves to the discharge pipe 16, the magnetic plate 33 will magnetically attract the pressure plate 30. At this time, the pressure plate 30 will squeeze the collecting block 27, thereby squeezing the sponge block 29. At this time, the liquid absorbed by the sponge block 29 can flow into the collecting block 27 and then be discharged from the discharge pipe 16. Through the above mechanism, the sponge block 29 is squeezed, thereby allowing the liquid absorbed by the sponge block 29 to be discharged. When the sponge block 29 is squeezed, the liquid will diffuse from all sides of the sponge block 29. The liquid that diffuses to the top of the sponge block 29 will flow onto the guide block 31 and then flow into the collecting block 27 through the round hole 32.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A combined preparation apparatus for methylhydrazine, comprising an evaporator crystallizer (11), a forced circulation evaporator (7), a distillation column (1), a crystallization circulation pump (3), a thickener (12), a falling film evaporator (8), a thermosiphon reboiler (9), a falling film circulation pump (5), a forced circulation pump (2), a bottom pump (6), and a horizontal centrifuge (36); characterized in that: The evaporator crystallizer (11) is connected to the forced circulation pump (2) through a pipe. The forced circulation pump (2) is equipped with a forced circulation evaporator (7) at its inlet and outlet respectively. The evaporator crystallizer (11) is located inside the distillation column (1). The evaporator crystallizer (11) is connected to the crystallization circulation pump (3) through a pipe. The crystallization circulation pump (3) is connected to the thickener (12) through a pipe. The falling film evaporator (8), the thermosiphon reboiler (9), and the falling film circulation pump (5) are located at the bottom of the distillation column (1). The outlet of the bottom pump (6) is connected to a discharge pipe (16). An electric rail (22) is fixedly connected to the surface near the bottom of the distillation column (1). A guide block (23) is slidably connected to the inner wall of the electric rail (22). A magnetic block (24) is provided on the top surface of the guide block (23). A cleaning block (21) made of magnetic material is attached to the inner wall of the distillation column (1). The cleaning block (21) and the magnetic block (24) are magnetically attracted. The magnetic block (24) is slidably connected to the top surface of the slider. A driving block (26) is fixedly connected to the top surface of the magnetic block (24). One side of the driving block (26) is inclined. A set of round rods (25) that push the driving block (26) are fixedly connected to the outer wall of the distillation column (1). A hollow connecting ring (17) is fixedly connected to the inner wall of the distillation column (1). An annular groove (18) communicating with the inside of the connecting ring (17) is opened on the bottom surface of the connecting ring (17). A connecting rod (19) passing through the groove (18) is fixedly connected to the top surface of the cleaning block (21). A connecting plate (20) is fixedly connected to the top end of the connecting rod (19). The side wall of the connecting plate (20) is in contact with the inner wall of the connecting ring (17).

2. The apparatus for the combined preparation of methylhydrazine according to claim 1, characterized in that: The distillation column (1) is equipped with a demister (13), a steam compressor (15), a reflux tank (14) and a condenser (10) at the top of the column. The reflux tank (14) is connected to a reflux pump (4) via a pipeline.

3. The apparatus for the combined preparation of methylhydrazine according to claim 2, characterized in that: The surface of the cleaning block (21) is fixedly connected with a "U"-shaped collection block (27). The collection block (27) is close to the inner wall of the distillation column (1) on both sides, and one of the sides is provided with a liquid outlet hole (28). The position of the liquid outlet hole (28) is aligned with the middle part of the discharge pipe (16). The top surface of the collection block (27) is open, and the collection block (27) is made of elastic material.

4. The apparatus for the combined preparation of methylhydrazine according to claim 3, characterized in that: A sponge block (29) is fixedly connected to the open end of the collection block (27).

5. The apparatus for the combined preparation of methylhydrazine according to claim 4, characterized in that: A magnetic plate (33) is fixedly connected inside the discharge pipe (16), and a pressure plate (30) that attracts the magnetic plate (33) is fixedly connected to the side of the collection block (27) away from the inner wall of the distillation column (1). The pressure plate (30) is made of magnetic material.

6. The apparatus for the combined preparation of methylhydrazine according to claim 5, characterized in that: Guide blocks (31) are fixedly connected to both sides of the inner wall of the collecting block (27). The top surface of the guide block (31) is inclined, and the guide block (31) is evenly provided with round holes (32) that communicate with the inside of the collecting block (27).

7. The apparatus for the combined preparation of methylhydrazine according to claim 6, characterized in that: A hollow elastic block (34) is fixedly connected inside the sponge block (29), and an air vent (35) is opened on the bottom surface of the elastic block (34).

8. A method for the combined preparation of methylhydrazine, using the methylhydrazine combined preparation apparatus as described in claim 7, characterized in that: Includes the following steps: S1: Methylhydrazine raw material is transported to the evaporator crystallizer (11) through the pipeline. The material in the crystallizer is pushed to establish circulation by the forced circulation pump (2). Forced circulation evaporators (7) are set at the inlet and outlet of the forced circulation pump (2) to heat the material. The steam at the top of the distillation column (1) is used as the heat source. S2: The evaporated gas in the evaporator crystallizer (11) enters the distillation column (1) by pressure. After the salts in the feed are enriched, they crystallize and precipitate. The crystallization circulation pump (3) transports the precipitator (12) for temporary storage. The solids are then separated by a horizontal centrifuge (36). The solid salts are discharged, and the liquid mother liquor is temporarily stored in the mother liquor tank and pressurized by the mother liquor pump before returning to the evaporator crystallizer (11). S3: The vapor phase of the evaporation crystallization enters the distillation column (1). At this time, the falling film circulation pump (5) provides power for the material circulation. The falling film evaporator (8) is the main heat source, using the pressurized top steam as the heat source. The thermosiphon reboiler (9) is the auxiliary heat source, using external steam as the heat source. The concentrated methylhydrazine aqueous solution at the bottom of the column is collected as a product by the bottom pump (6) and then discharged from the discharge pipe (16), completing the joint preparation of p-methylhydrazine.

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